null in merge result of an empty node set

[vvvy]

If a new set is created by ++ of an empty result of diSuccessors (in first place) and of some other non-emplty node set, the new set erroneously contains null in place of the empty set.

Consider the following code snippet:

import scalax.collection.Graph
import scalax.collection.GraphPredef._, scalax.collection.GraphEdge._
import scalax.collection.edge._

val g = Graph(1 ~> 2, 2 ~> 3)
((g get 3) diSuccessors) ++ ((g get 1) diSuccessors) //ORDER MATTERS!

The last expession yields to Set(null, 2) rather than Set(2).

I used graph-core_2.9.2-1.6.2.jar from Maven with Scala 2.9.3.

[peter-empen]

Thanks for reporting! 9525531 resolves this issue that will be included in the next release. Until then you may build the executable on your own via SBT or work around it by either using ++= or calling toSet like

((g get 3) diSuccessors).toSet ++ ((g get 1) diSuccessors)

Peter